1. Field of the Invention
The present invention relates generally to a gas appliance, and more particularly to a gas appliance and a method of controlling the gas appliance.
2. Description of the Related Art
Gas appliances, which are the device burning gas to perform a specific function, such as gas water heater, gas stove, gas clothing dryer and gas fireplace, have a high level of safety issue in home life. However, aging and malfunction are the main problem that causes danger in running of the gas appliance, and they have to be detected immediately and to get fixed or stopped in the following.
Typically, some data of the gas appliance are detected to ensure the appliance in normal running, such as heat efficiency, gas concentration, gas pressure, and running data of some key elements of the gas appliance. The gas appliance usually is provided with a pressure gauge, such as U-tube gauge and Bourdon-tube gauge, to measure the gas pressure. The U-tube gauge provides water or mercury in a U-shaped tube. The surfaces of the mercury will be at the same level when the pressures on the opposite ends of the U-shaped tube are the same, and there will be a height difference between the mercury surfaces when the pressures are different. One may find the pressure according to the height difference.
The Bourdon-tube gauge has a copper alloy tube, which has an elliptical cross section and is bent into a curved shape. An end of the tube is connected to a connector. The distal end of the tube is closed, and there is a space for the tube to expand. When a pressure is transmitted to the tube 90 through the connector, the curved tube will be extended. A link connects the distal end of the tube and a sector gear. The sector gear is provided with a pointer on a scale to show the value of pressure. In other words, the pressure may deform the tube to move the pointer through the link, and the pressure is directly proportional to the deformation of the tube that the movement of the pointer may indicate the pressure.
There are several drawbacks in the conventional pressure gauges, for example, the U-tube gauge has a poor precision in measurement, and the U-shaped tube usually is made of class which is easy to be broken. Besides, the temperature in the U-shaped tube will affect the precision of measurement. For the Bourdon-tube gauge the temperature affects the precision of measurement also, and the material fatigue of the copper tube is another big problem.
In conclusion, there still are some places in the art of pressure detection for the automatic control of the gas appliance that needs to be improved.